The two types of finger actuated pumps currently in use are the "throttling" and "non-throttling" systems. Both consist of a valve body housing a plunger acting against a return spring and both also utilize a check valve in the suction and discharge ports. The basic difference between the two is in the method of opening the discharge valve. The "throttling" type generally utilizes a free floating ball while the "non-throttling" type has a spring loaded valve; the spring usually being the same one that returns the plunger to the inactive position.
The terms "throttling" and "non-throttling" describe the control the user has over the discharge. In the "throttling" type, once the system has been primed, flow commences immediately from the dispenser spout as the button is depressed since the discharge check valve offers no resistance to the opening pressure. The user can control the pressure, rate of flow and amount discharged by varying the speed, force and deflection of the activator button; hence, the term "throttling". In the "non-throttling" version, the user must exert enough finger pressure to raise the internal pressure sufficiently high in order to overcome the spring force holding the discharge valve closed. Once this force is exceeded, the discharge valve opens and allows product to flow out into the dispenser spout at a pressure equal to that in the valve housing. As soon as the pressure drops, as, for example, the user stops the downward force on the dispenser spout or the plunger reaches the end of its stroke, the spring loaded discharge valve snaps shut, cutting off any further flow. The advantage of this system over the first is that flow occurs only at a certain minimum pressure and is primarily used for products that must be atomized, such as hair sprays and the like where high pressures and fast shut off are required.
The invention described herein was developed primarily for use with products requiring atomization and designed to overcome the deficiencies inherent in present so-called "non-throttling" pumpsby dividing the input of the user and the output of the valve into two separate yet mutually dependent motions.